[syzbot] [bpf?] possible deadlock in deactivate_slab

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c3f38fa61af7 Linux 6.10-rc2
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12e9d362980000
kernel config: https://syzkaller.appspot.com/x/.config?x=998c63c06e77f5e7
dashboard link: https://syzkaller.appspot.com/bug?extid=a4acbb99845d381e5e2f
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-c3f38fa6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/af6a0b581dee/vmlinux-c3f38fa6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/47864da8bd74/bzImage-c3f38fa6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a4acbb...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.10.0-rc2-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.1/23904 is trying to acquire lock:
ffff888040002018 (&n->list_lock){-.-.}-{2:2}, at: deactivate_slab+0x2b4/0x4a0 mm/slub.c:2948

but task is already holding lock:
ffff88802792d9f8 (&trie->lock){-.-.}-{2:2}, at: trie_update_elem+0xc7/0xdb0 kernel/bpf/lpm_trie.c:333

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&trie->lock){-.-.}-{2:2}:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
trie_delete_elem+0xb0/0x820 kernel/bpf/lpm_trie.c:462
0xffffffffa0001fd2
bpf_dispatcher_nop_func include/linux/bpf.h:1243 [inline]
__bpf_prog_run include/linux/filter.h:691 [inline]
bpf_prog_run include/linux/filter.h:698 [inline]
__bpf_trace_run kernel/trace/bpf_trace.c:2403 [inline]
bpf_trace_run2+0x231/0x590 kernel/trace/bpf_trace.c:2444
trace_contention_end.constprop.0+0xea/0x170 include/trace/events/lock.h:122
__pv_queued_spin_lock_slowpath+0x28e/0xcc0 kernel/locking/qspinlock.c:557
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:584 [inline]
queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
queued_spin_lock include/asm-generic/qspinlock.h:114 [inline]
do_raw_spin_lock+0x210/0x2c0 kernel/locking/spinlock_debug.c:116
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline]
_raw_spin_lock_irqsave+0x42/0x60 kernel/locking/spinlock.c:162
get_partial_node.part.0+0x20/0x350 mm/slub.c:2675
get_partial_node mm/slub.c:2672 [inline]
get_any_partial mm/slub.c:2759 [inline]
get_partial mm/slub.c:2793 [inline]
___slab_alloc+0xd36/0x1870 mm/slub.c:3646
__slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3756
__slab_alloc_node mm/slub.c:3809 [inline]
slab_alloc_node mm/slub.c:3988 [inline]
kmem_cache_alloc_noprof+0x2ae/0x2f0 mm/slub.c:4007
getname_flags.part.0+0x50/0x4f0 fs/namei.c:139
getname_flags include/linux/audit.h:322 [inline]
getname+0x8f/0xe0 fs/namei.c:218
do_sys_openat2+0x104/0x1e0 fs/open.c:1399
do_sys_open fs/open.c:1420 [inline]
__do_sys_openat fs/open.c:1436 [inline]
__se_sys_openat fs/open.c:1431 [inline]
__x64_sys_openat+0x175/0x210 fs/open.c:1431
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&n->list_lock){-.-.}-{2:2}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
lock_acquire kernel/locking/lockdep.c:5754 [inline]
lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
deactivate_slab+0x2b4/0x4a0 mm/slub.c:2948
___slab_alloc+0xc0b/0x1870 mm/slub.c:3591
__slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3756
__slab_alloc_node mm/slub.c:3809 [inline]
slab_alloc_node mm/slub.c:3988 [inline]
__do_kmalloc_node mm/slub.c:4120 [inline]
__kmalloc_node_noprof+0x36c/0x450 mm/slub.c:4128
kmalloc_node_noprof include/linux/slab.h:681 [inline]
bpf_map_kmalloc_node+0x98/0x4a0 kernel/bpf/syscall.c:422
lpm_trie_node_alloc kernel/bpf/lpm_trie.c:299 [inline]
trie_update_elem+0x1ef/0xdb0 kernel/bpf/lpm_trie.c:342
bpf_map_update_value+0x2c1/0x6c0 kernel/bpf/syscall.c:203
generic_map_update_batch+0x454/0x5f0 kernel/bpf/syscall.c:1889
bpf_map_do_batch+0x615/0x6e0 kernel/bpf/syscall.c:5196
__sys_bpf+0x18cb/0x5830 kernel/bpf/syscall.c:5751
__do_sys_bpf kernel/bpf/syscall.c:5794 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5792 [inline]
__ia32_sys_bpf+0x76/0xe0 kernel/bpf/syscall.c:5792
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
entry_SYSENTER_compat_after_hwframe+0x84/0x8e

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&trie->lock);
lock(&n->list_lock);
lock(&trie->lock);
lock(&n->list_lock);

*** DEADLOCK ***

2 locks held by syz-executor.1/23904:
#0: ffffffff8dbb5160 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
#0: ffffffff8dbb5160 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:781 [inline]
#0: ffffffff8dbb5160 (rcu_read_lock){....}-{1:2}, at: bpf_map_update_value+0x24b/0x6c0 kernel/bpf/syscall.c:202
#1: ffff88802792d9f8 (&trie->lock){-.-.}-{2:2}, at: trie_update_elem+0xc7/0xdb0 kernel/bpf/lpm_trie.c:333

stack backtrace:
CPU: 3 PID: 23904 Comm: syz-executor.1 Not tainted 6.10.0-rc2-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137
lock_acquire kernel/locking/lockdep.c:5754 [inline]
lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
deactivate_slab+0x2b4/0x4a0 mm/slub.c:2948
___slab_alloc+0xc0b/0x1870 mm/slub.c:3591
__slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3756
__slab_alloc_node mm/slub.c:3809 [inline]
slab_alloc_node mm/slub.c:3988 [inline]
__do_kmalloc_node mm/slub.c:4120 [inline]
__kmalloc_node_noprof+0x36c/0x450 mm/slub.c:4128
kmalloc_node_noprof include/linux/slab.h:681 [inline]
bpf_map_kmalloc_node+0x98/0x4a0 kernel/bpf/syscall.c:422
lpm_trie_node_alloc kernel/bpf/lpm_trie.c:299 [inline]
trie_update_elem+0x1ef/0xdb0 kernel/bpf/lpm_trie.c:342
bpf_map_update_value+0x2c1/0x6c0 kernel/bpf/syscall.c:203
generic_map_update_batch+0x454/0x5f0 kernel/bpf/syscall.c:1889
bpf_map_do_batch+0x615/0x6e0 kernel/bpf/syscall.c:5196
__sys_bpf+0x18cb/0x5830 kernel/bpf/syscall.c:5751
__do_sys_bpf kernel/bpf/syscall.c:5794 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5792 [inline]
__ia32_sys_bpf+0x76/0xe0 kernel/bpf/syscall.c:5792
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf731f579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f5f115ac EFLAGS: 00000292 ORIG_RAX: 0000000000000165
RAX: ffffffffffffffda RBX: 000000000000001a RCX: 0000000020000100
RDX: 0000000000000038 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
0: 10 06 adc %al,(%rsi)
2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi
6: 10 07 adc %al,(%rdi)
8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi
c: 10 08 adc %cl,(%rax)
e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi
1e: 00 51 52 add %dl,0x52(%rcx)
21: 55 push %rbp
22: 89 e5 mov %esp,%ebp
24: 0f 34 sysenter
26: cd 80 int $0x80
* 28: 5d pop %rbp <-- trapping instruction
29: 5a pop %rdx
2a: 59 pop %rcx
2b: c3 ret
2c: 90 nop
2d: 90 nop
2e: 90 nop
2f: 90 nop
30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi
37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi


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